The inhibition effects of reactive oxygen species by Maillard reaction products in Caco-2 cells

Maillard reaction products (MRPs) were prepared by heating a mixture of rice starch with different dextrose equivalents (DE 10, 30, 50 and 70) and glycine. The glycine was added to the sample pastes at the same molar concentration as the sugar contained in each sample. As the dextrose equivalent of rice starch increased, the browning intensity and fluorescence of the MRPs increased. The antioxidant properties of the MRPs were investigated by DPPH radical scavenging activity, reducing power, and phenolic content in a chemical system, and were evaluated by measuring reactive oxygen species levels and antioxidant enzymes activities in Caco-2 cells. The darkest MRPs, MRPs-4, showed the highest antioxidant activity and phenolic content among the samples; in addition, it inhibited the cellular oxidative stress. The decrease of cell viability and antioxidant enzymes activities caused by reactive oxygen species and apoptosis were recovered by MRPs-4. Actually, the addition of the MRPs suppressed apoptosis by decreasing the proportion of cells in the sub-G1 phase. Therefore, these MRPs, as compounds formed by the Maillard reaction, are considered to possess an effective antioxidant activity against oxidizable substrates.